Theory of the sun and the moon

The Sun and Moon Allegory is used to image a medieval political theory that was espoused by the Roman Catholic Church and instantiated to some extent in medieval political practice. Finding this imagery in the Book of Genesis, the Allegory images authentic spiritual authority as the Sun and any and all civil, or political or secular, authority as the Moon. By doing so, it illustrates that the Roman Catholic Pope, as "Supreme Pontiff", "Vicar of Christ", et cetera, and therefore the supreme universal spiritual authority on Earth, is like the Sun that is the one source of light for itself and all other celestial bodies orbiting it; while the Holy Roman Emperor, as symbolic and intended supreme civil, political, and secular authority on Earth, and having theoretically received his authority from and at the pleasure of the Pope, is like the Moon - that is, dependent upon the Sun for any illumination, merely reflects solar light, and ultimately has no light without the Sun. This theory dominated European political theory and practice in the 13th century. It is related to the general theory of Papal supremacy and "plenitudo potestatis" as articulated by the Roman Catholic Church.

An affirmation of this view, which the Lateran Council confirmed, is contained in the letters of Pope Innocent III: "The Lord gave [St.] Peter the rule not only over the universal Church, but also the rule over the whole world." "No king can reign rightly unless he devoutly serves Christ's Vicar." "The priesthood is the Sun, the kingdom the Moon. Kings rule over their respective kingdoms, but [St.] Peter rules over the whole Earth."

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